An apparatus disclosed in, for example, Japanese Patent No. 4631327 (Reference 1) has been known as a vehicle seat slide apparatus. As shown in FIG. 5, the apparatus includes a lower rail 92 which is fixed to a vehicle floor 91 and extends along a front-rear direction, an upper rail 93 which is slidably mounted to the lower rail 92, a lateral slide rail 95 which is provided in the upper portion of the upper rail 93 in a vehicle width direction and slidably supports a seat 94, a first lock mechanism 96 capable of fixing the upper rail 93 to an arbitrary position of the lower rail 92, and a second lock mechanism 97 which selectively restricts a movement of the upper rail 93 in a rearward direction from a predetermined position. When the seat 94 is within a predetermined range in the vehicle width direction, the second lock mechanism 97 restricts the movement of the upper rail 93 in the rearward direction from the predetermined position by locking a stopper unit 98 to a bracket 100 fixed and mounted to the lower rail 92 in a locked state with a stopper bracket 99 where the stopper unit 98 rotatably supported to the upper rail 93 is held in an upright position by the stopper bracket 99 fixed to the seat 94.
Moreover, if the seat 94 is moved in the vehicle width direction by the lateral slide rail 95, the second lock mechanism 97 allows the movement of the upper rail 93 in the rearward direction from the predetermined position by releasing the locked state between the stopper unit 98 and the stopper bracket 99.
That is, in the case where the seat 94 is within the predetermined range in the vehicle width direction, when the upper rail 93 (seat 94) is moved in the rearward direction, it is possible that the upper rail 93 is temporarily stopped at the predetermined position and then moved in the rearward direction further than the predetermined position. Thus, particularly when the upper rail 93 is moved widely, it is possible to reduce the movement speed of the upper rail 93. Thereby, it can be prevented that the seat 94 hits peripheral equipment such as a wheel house with a large impact force.
Meanwhile, In the Reference 1, the restriction or release of the movement of the upper rail 93 in the rearward direction from the predetermined position due to the engagement or disengagement between the stopper unit 98 and the stopper bracket 99 of the second lock mechanism 97 is switched corresponding to the position of the seat 94 in the vehicle width direction. In other words, when the seat 94 is out of the predetermined range in the vehicle width direction in advance, the movement of the upper rail 93 in the rearward direction from the predetermined position is always allowed. However, demands related to a positional adjustment of the seat 94 or the like are various. As an example of the demands, a user may want to always restrict the movement of the upper rail 93 with respect to the lower rail 92 at a predetermined position within a movable range of the upper rail 93. Specifically, in the seat which is slidable between the first row and the second row of the rear-seat compartment, when moving the seat from a front area, namely the first row, to a rear area, namely the second row, there may be a case of temporarily stopping the seat at a boundary position between the front area and the rear area in order to allow a user to recognize the change of the area. Alternatively, when moving the seat from a seating area to a non-seating area (luggage compartment area, for example), there may be a case of temporarily stopping a seat body at the boundary position between the seating area and the non-seating area in order to allow a user to recognize the change of the area.
Meanwhile, even in the case where the seat is temporarily stopped at the boundary position between both areas, or the like, if a user returns the seat to the original area where the seat was located before being moved toward the boundary position, or the like, it is preferable to release the movement restriction of the upper rail by a simple operation because the change of area between both areas practically does not occur. That is, if, for example, the release operation of an operation lever is required to release the movement restriction of the upper rail at the boundary position between both areas, or the like, there is a possibility that the operationality may be deteriorated.
A need thus exists for a vehicle seat slide apparatus which is not susceptible to the drawback mentioned above.